A diabetic measures blood sugar several times a day by himself/herself. During the measurement, the diabetic must collect a small amount of blood from a fingertip or the like. For this purpose, as shown in FIG. 13, a disposable puncture needle 105 is attached to an instrument called a lancet 101, and a fingertip or arm is punctured with the needle 105, and blood collected from the punctured region is used for measurement.
The common lancet 101 comprises a cylindrical body 130, and a cap 153. The cylindrical body 130 is provided with a first spring 132 for projecting the attached puncture needle 105, a second spring 134 for backing off the projected puncture needle 105, and an injection button 117 for releasing the compressed first spring 132.
The lancet 101 is used as follows. Initially, the cap 153 is removed from the cylindrical body 130, and the puncture needle 105 is attached to the cylindrical body 130, and then the cap 153 is again put on the cylindrical body 130. Then, the first spring 132 is compressed to set the lancet 101 in a state where puncture is possible, and a puncture target pressing surface 136 of the cap 153 is applied to a target to be punctured, such as a fingertip. When the injection button 107 is pushed, the puncture needle 105 is projected to puncture the target. After the puncture, the puncture needle 105 is immediately removed from the fingertip or the like by the second spring 134. Through the above-mentioned operations, blood is collected. It is very dangerous from a hygienic perspective to reuse the once-used puncture needle 105, and therefore, it is necessary to replace the puncture needle 105 with a new one at next use. (Refer to Japanese Published Patent Application No. 2000-237172).
On the other hand, there is a lancet which holds a plurality of puncture needles, and performs puncture using these puncture needles one by one in turn. After the puncture, the puncture needles can be individually removed from the lancet. This lancet utilizes the elasticity of a flat spring attached to the puncture needle as a driving means for reciprocating the puncture needle. (Refer to U.S. Pat. No. 4,794,926).
By the way, the user believes that the many stages of manual operation using the conventional lancet system, i.e., the above-mentioned puncture needle and puncture operation steps, are troublesome. Therefore, the user is apt to use a once-inserted puncture needle several times for puncture and blood collection. It should be avoided for hygienic reasons to use one puncture needle several times, especially, using one puncture needle for two or more persons. Such situation might occur in, for example, a clinic or a hospital, and a case where a child uses the once-used puncture needle by mistake cannot be excluded.
On the other hand, since a puncture needle is manufactured as a single-use needle, the needle tip becomes dull in a short time if it is used several times, and therefore, successive use of the puncture needle causes more pain to the patient. Furthermore, it is feared that the conventional puncture needle cannot be accurately inserted into the conventional lancet. Further, when the puncture needle and the lancet are improperly used, the user might be wounded.
As described above, in the conventional lancet system, there is a danger that the user might be wounded in his fingertip with the used puncture needle when replacing the puncture needle. Further, since the patient measures blood sugar several times a day, replacement of the puncture needle is very troublesome for the patient. Especially, it is a serious program for a patient who is visually handicapped due to complications associated with diabetes.